Crystallum Cadens
by cryptologicalMystic
Summary: Homura Akemi falls into the Underground in Frisk's place. Chaos theory takes hold, Alphys and Undyne come into the picture much earlier than expected, and Sans begins to regain the slightest bit of hope. [Canon-typical Alphyne, minor-ish MadoHomu] [Officially on HIATUS]
1. Delapsa

Crossposted to ArchiveOfOurOwn.

AO3 tags that aren't already in the summary/etc.: Mutually Fictional, (sort of), Anime Is Real, Video Game Mechanics, Soft Chara, Confused Alphys, Sufficiently Omniscient Madokami, 'sufficiently' a word which here means 'enough to be able to do advanced mathematics', References to Undertale Genocide Route, homura and sans are both broken in pretty much some of the exact same ways

This will update sporadically, if at all. I am not good with schedules.

[ALL CAPITALS IN SQUARE BRACKETS] - W. D. Gaster speaking  
 _Italics_ \- normal thoughts  
{In curly brackets} - telepathy  
 **Bold** \- video game text, etc.

* * *

／人◕ ‿‿ ◕人＼

* * *

Consciousness returned to Homura slowly, dripping into her mind like meltwater from ice. As she righted herself, she glanced up at the hole in the sky, surrounded by ancient-seeming pillars, and remembered - she had been tracking a nest of wraiths, up a mountain nearby Mitakihara, hadn't she? Yes - but then it had begun to rain, and she had ducked into a nearby cave for a moment. (Why?)

Unfortunately, the cave had been entirely in shadow, and so she hadn't seen the hole until it was too late.

Well, that was easily fixed. Homura focused for a moment, summoning first her Puella Magi outfit, then her wings. With a jump and a flutter of luminous feathers, she was airborne, heading for the pinprick of sky up above -

 _Bam_. Her face slammed into an invisible ceiling. It seemed that that would not be a viable way out.

She carefully glided back down, not wanting to injure her body more than she already had, dismissed her wings, and set to work healing her face. The process was both sluggish and magic-intensive, given that she wasn't a natural healing mage (best not to think about Miki, now, Miki who was in a better place), so she did only the bare minimum. Bloody noses were not conducive to anything resembling efficiency.

Her Soul Gem was about a third darkened; she would need to recharge soon, but not yet. She checked in her inventory, and found eight cubes - more than enough, for now.

Homura stood once more, and saw a path leading out of the small cavern, towards a door elegantly carved from the surrounding stone.

Perhaps it led to a way back up.

* * *

Let me stop for a moment to clarify something about Puellae Magi.

In the anime, Homura Akemi is seen using her shield as a storage space, with a large enough volume to hold several timelines' worth of military weaponry. Most authors write this as an inherent property of the shield; however, for purposes of this fic, I have decided that Puellae Magi in general all have inventories of varying size, vaguely related to their magical potential (with a not insignificant margin of error), and more strongly related to their wish, if said wish might conceivably have an effect.

Where else would Mami have gotten that teacup in Episode 2, after all? I doubt it came from Gertrud's barrier, or that Mami would have sipped from it if it had.

Size of Homura's inventory post-Madoka: About the size of a very small room. Let's say 3.476 cubic feet. (This is above average.)

Size of Homura's inventory pre-Madoka: Big. (I'm not specifying this because I am lazy and have no idea how much she was seen to have in there over the course of the entire anime.)

* * *

In the next room, there was a flower. With a face.

Homura stared at the flower, which grinned back.

"Howdy!" it chirped cheerfully, in an all-too-saccharine voice, and Homura barely restrained herself from summoning her bow and shooting it right then and there. "I'm Flowey. Flowey the flower!"

"...," Homura boggled, thanking her past self for taking the time to become fluent in English. The flower was pinging her magic sense, as were several more entities past it; however, they didn't register as either wraiths or witches. Their signatures lacked a lot of the despair that characterized both.

"Hmm," the flower - Flowey - continued, "you're new to the Underground, aren'tcha? Golly, you must be so confused. Someone ought to teach you how things work around here!"

Homura was indeed quite confused, but she had no intention of showing it.

"I guess little old me will have to do. Ready?" Flowey didn't wait for a response. "Here we _go_ —"

The surroundings rapidly darkened, and a sudden force pulled Homura's gem from her hand and to her chest before she could resist.

 **Homura LV 1 HP 80/80 MP 19401/27796**

Since when had reality been a video game?

"See that heart? That is your soul, the very culmination of your being!"

Homura looked down, and yes, her gem had in fact reshaped itself into a stylized heart, floating in front of her. Strangely, the majority of it was colored a bright red; the only place she could see her distinctive purple was at the very edges. She belatedly realized that, despite not having her wings out, she was floating along with it. Odd. Glancing suspiciously at the flower, which seemed to have allowed her time to acclimate herself, she discovered that the principles of movement were similar to those of her wings - if she willed motion, her soul would move, and she would move along with it.

"Your soul starts off weak," Flowey went on, apparently deciding that she had had enough time, "but can grow strong if you gain LV! What's LV stand for?"

If it truly was a video game, then it probably stood for 'level'.

"Why, LOVE, of course!"

That made no sense. The word 'love' was already short enough, why would it need to be shortened more? 'Flowey' had suddenly upgraded from 'suspicious' to very suspicious.

"You want some LOVE, don't you? Don't worry, I'll share some with you!" The flower winked, and an honest-to-god _anime sparkle_ drifted away from its head.

What.

"Down here," Flowey exposited, several very deadly-looking magical manifestations spawning around its body, "LOVE is shared through... little white..." Its eyes shifted to the left for a split second, and Homura tensed, recognizing the obvious sign of a lie. "...'friendliness pellets'."

Enough was enough. "No, thank you."

"Are you rea—" Flowey paused in the middle of its sentence, looking taken aback. "...wait, what?"

"You have given me no reason to trust you," Homura stated plainly.

The flower was speechless for a moment. A demonic grin slowly spread on its face. "You know what's going on here? I'm surprised. You're less of an idiot than I thought."

A sphere of bullets appeared around Homura.

"Too bad for you!" Flowey crowed. "In this world, it's kill or be killed."

The bullets began to close in on her.

" _ **Die.**_ "

There was no visible escape. The projectiles were too close together.

Was this really how she would meet her end?

Even though she had survived hundreds of Walpurgisnachts, that meant nothing when certain death couldn't be averted with a thought and a twist of her shield.

Homura had hoped for despair. Then, at least...

 _Madoka... I'm sorry._

A glowing fireball smashed into Flowey, knocking it screeching to the side. The bullets it had summoned disappeared, and Homura's soul returned to its place on her hand.

"What a terrible creature, torturing such a poor, innocent youth..."

* * *

Four figures watched from within a place that could not by its very nature be within the universe.

The first was a skeletal man with holes in his hands and cracks in his face, wearing a black cloak. This was Dr. W. D. Gaster.

The second was a child with a determined expression, outlined in a dark red. This was Frisk.

The third was a girl in a pink dress, holding a bow. This was Madoka Kaname.

The fourth figure, outlined in a red that was almost pinkish, was another child, standing apart from the others. Their wrists were manacled, and their face seemed to be in conflict between guilt, resentment, fear, and LOVEly malice. They were rubbing their handcuffs as if to make sure they were still there. This was Chara Dreemurr.

"It's going well so far," Madoka mused. "I'm worried for Homura-chan, though... I know you've done the calculations, Dr. Gaster, I checked them myself and they seem right as far as I can tell, but I still can't help wondering - what if something goes wrong? What if she can't use the SAVE points, or there's complications with the spatiotemporal graft, or... I know, it's silly, but so much depends on her taking a nonviolent path, and Homura... she... wasn't the most nonviolent person, either."

[THERE IS NOT MUCH I CAN DO TO SOOTHE YOUR MIND,] signed Gaster, [OTHER THAN TO REMIND YOU THAT NO SEQUENCE OF EVENTS IS UNIQUE, AND THAT THIS UNIVERSE IS MORE LIKELY TO SUCCEED BY ITS VERY NATURE OF INTERACTION.]

As he spoke, Frisk reached up to give Madoka's shoulder a reassuring pat.

"That does actually help, a little..."

Chara turned away, and said nothing. They were not smiling.

* * *

／人◕ ‿‿ ◕人＼

* * *

Reviews are appreciated - even negative ones, provided they tell me what they specifically disliked.

Again, this will update sporadically, if at all, because I'm not good with schedules.


	2. Intentio Inutilis

Possible trigger warning for **suicide**.

[ALL CAPITALS IN SQUARE BRACKETS] - W. D. Gaster speaking  
 _Italics_ \- normal thoughts  
{In curly brackets} - telepathy  
 **Bold** \- video game text, etc.

* * *

／人◕ ‿‿ ◕人＼

* * *

A tall goat woman with cinnamon-colored eyes, dressed in purple and white robes, stood where Flowey had been, her paw-like hand burning with ivory flame. "Ah, do not be afraid, my child. I am Toriel, caretaker of the Ruins. I pass through this place every day to see if anyone has fallen down. You are the first human to come here in a long time."

"...I am Homura Akemi," Homura replied, after a pause. "I know your name, but... what are you?" If humans were not a common sight, then what lived here? What was Toriel, that she and hers radiated magic without being either Puella Magi or wraith?

"My species," Toriel said kindly as Homura stood, "is called 'monsters'. However, we are not generally so monstrous as the name implies; quite the opposite, in fact. That flower - the one I just knocked away - seems to have been an exception." She frowned. "A rather... vicious exception."

"The flower..." Homura thought out loud. "It attempted to draw me in with a false explanation of my soul. Or, at least, it appeared false. I've played video games before, though not in a long time." It had been more than two decades, to be slightly more exact, though she had no intention of saying so. "I doubt that LV actually stands for LOVE."

Toriel hesitated. "You... would not be completely wrong. It is a recursive acronym of sorts - LV stands for LOVE, but LOVE stands for 'level of violence'. It serves as a measure of how willing one is to inflict suffering."

"Ah," Homura said, because there was really nothing else she could say to that.

A cough from Toriel. "...Anyway! Onwards to more palatable subjects."

They had passed through a room with a set of stairs and a leaf pile (the leaves contained a small golden sparkle, which vaguely interested Homura for a reason she couldn't place), entering a vaguely octagonal room. The floor boasted three columns of two pressure plates each; the opposite wall held a gilded lever, a large stone door, and a sign.

 _Only the fearless may proceed. Brave ones, foolish ones. Both walk not the middle road._

In Homura's experience, bravery and foolishness were often the exact same thing.

"The Ruins are full of puzzles," Toriel explained, triggering the outer columns of pressure plates, "ancient fusions between diversions and doorkeys. One must solve them to move from room to room." She flipped the switch, and the door opened with a groan. "Please adjust yourself to the sight of them."

The two of them went through the door. The next room, Homura saw, had three more switches, two of them labeled in yellow, and two signs.

 _Stay on the path_ , said one.

The other, however...

 _Press [X] to read signs!_

Homura suddenly understood even less than before.

...Anyway. That didn't matter right now. She could ask Toriel about it later.

"I assume that the levers marked in yellow are the ones to pull?"

"Yes! Well done!"

They crossed the spikes into yet another room. This one held a stuffed dummy, and a door on the left. No puzzle was obvious.

"As a human living in the Underground," Toriel exposited, "monsters may attack you. You will have to be prepared for this situation."

Homura nodded. If she understood anything about the world, it was that fighting would be inevitable.

"Worry not, however! The process is simple. When you encounter a monster, you will enter a fight. While you are in a fight, strike up a friendly conversation. Stall for time, and I will come to resolve the conflict."

Wait, what?

...oh. Monsters as a species. A sapient species, with no revival mechanism like the Incubators had. If she harmed one beyond repair, it would be permanent, especially without the ability to rewind.

What would Madoka say, if someone died by Homura's hand?

(That question - what would Madoka say, what would Madoka do - had been a cornerstone of Homura's morality ever since the world was rewritten.)

"You may practice talking to the dummy, if you wish," Toriel smiled.

Homura walked forward, stopping in front of the dummy. Her gem flashed, and a battle engaged.

 *** You encountered the Dummy.**  
 **Homura Akemi LV 1 HP 80/80 MP 19399/27796**

It seemed that her MP had dropped by 2 since her encounter with the flower. Did MP correspond to the amount of usable magic remaining in her Soul Gem, then? It would certainly be a more effective (and convenient!) way of gauging corruption than weighing it and comparing the weight to when it had just been cleaned.

 **[Fight] [Act] [Item] [Mercy]**

Those four options - possibly indicative of a turn-based RPG - hadn't been there during the previous battle. Homura tapped Act, then the word Dummy, and a submenu came up.

Her options seemed to be **Check** and **Talk**. Out of curiosity, she chose **Check**.

 **Dummy - ATK 0 DEF 0**  
 *** It doesn't seem to be animate.**

The check text was confirmed, as the dummy passed its turn without doing anything. Talking seemed to be the obvious next option.

"...How has the weather been lately?"

For all the time she had spent in the loops, mastering anything that could possibly prove useful, small talk had never been something she had judged important.

The dummy remained where it was, seemingly about to fall over.

 *** You won!**  
 *** You gained 0 XP and 0 GOLD.**

"Splendid!" Toriel said, clapping. "Again, well done!"

* * *

They made it through the next room without incident. A 'Froggit' (having four ATK and four DEF, according to its **Check** option) had attempted to accost Homura, only for Toriel to intimidate it away. The room after that was a long hall, boasting a pillar at the end and absolutely nothing else.

That was quite a lot of empty space serving no purpose at all, wasn't it? Considering that the Ruins apparently held a surplus of puzzles, Homura wasn't going to rule out some sort of secret door.

Toriel stopped at the entrance. "You seem like a rather independent person," she told Homura. "Would you mind staying here while I attend to some business? It will take no more than a few minutes."

"That seems doable."

"Alright. Please remain in this room; it is dangerous to explore alone." Toriel paused, retrieving something from a pocket of her robe. "I have a spare cell phone which you can use to contact me. If you need anything, do not hesitate to call."

Homura accepted the phone without complaint; hers likely wouldn't work underground, with so much rock in the way. As Toriel continued on, she noticed a pile of leaves outside the exit, containing another golden sparkle like the one she had seen earlier.

What were those things, anyway?

Should she investigate the closest one? No - best to stay on Toriel's good side for now. On further reflection, this place was also a complete unknown. For all Homura knew, there was a pack of Froggits outside waiting to ambush her, or an expanse of crumbling ground, covering a bottomless pit, through which there was only one safe path, or -

 _Deep breaths. The future can wait._

Better the devil she knew.

The best option, it seemed, would be to go back and look at the sparkle in the other room. It would also provide an opportunity to observe the strange wall covering the hole in the mountain. Homura had memorized the spikes in the blueprint puzzle out of habit, so crossing the bridge would not be difficult. She turned away from the eastern exit, feet already in motion, and caught a glimpse of something yellow burrowing into the ground.

...That had looked a hell of a lot like Flowey. Homura summoned up her bow; she would have to be on guard.

* * *

The aforementioned flower, who had sprouted up behind the Puella Magi in the next room, paused for a moment and blinked several times to make sure he wasn't hallucinating.

That hadn't been a normal item retrieval. That had been...

Had that been human magic?!

* * *

A phone call from Toriel.

"Hello; this is Toriel. You have not left the room, have you?"

"I went backwards."

"...well. I suppose that it is better than having gone forwards. There are some puzzles ahead that I have not yet explained. It would be dangerous to try to solve them yourself, even if there were no hostile monsters nearby. In any case, my errands are taking somewhat longer than I thought they would. Will you be able to wait a few more minutes?"

"Yes."

"Alright, then. Be good, won't you?"

Click.

Homura stepped carefully down the stairs, heels crunching in the pile of cinnamon leaves. The star glinted invitingly just ahead with its own light. It didn't seem to be burning the leaves; she tested it with her hand, just in case. No sensation of heat, or indeed of cold.

Her hand met the star, and -

 *** (The discovery of a new form of magic, one that you doubt the Incubators knew about, fills you with determination.)**  
 *** (HP and MP fully restored.)**  
 *** (Would you like to SAVE?)**

Afterwards, Homura wouldn't be able to say why she had done it; after all, agreeing to random requests was hardly a good idea. But there was something red burning in her soul, something sublime that drove her to accept.

 **[File saved.]**  
 **[Homura Akemi - LV 1 - 03 Jun 2012 18:11 - Ruins Entrance]**

* * *

Sans usually stayed in bed in the morning for as long as possible before his brother forced him to get up. To put it lightly, he wasn't a fan of waking up and realizing that the kid had once again made time do backflips. Sleeping also raised one's HP above their maximum, a mechanic which he relied on heavily for day-to-day survival.

This time, though, he snapped awake all at once and proceeded to roll off his mattress.

 _oh no - oh no - frisk what the hell did you_ do _-_

He scrambled to his feet and began fumbling for his lab key, mentally rehashing the events of the last few timelines.

The eighth fallen human had always been a perfectionist from the very beginning. This had, at first, worked out very well; Frisk had spared their way through the Underground, befriending its inhabitants along the way, and eventually broken the barrier. It had been perfect, for a few moments. Sans had stared out at the sky, at the sunset, at the city in the distance, and thought: _this is it. the loops are over, i can relax._

But Frisk hadn't been able to save Asriel, and they were the one with absolute power over time.

Sans had woken up to his dirty little room in Snowdin, and stared at the ceiling for an hour, trying desperately not to cry.

He had already hated Flowey, for the temporal sociopathy that had driven an entire team of scientists to despair. He hated him even more, afterwards.

As Frisk had reset over and over, chasing an impossible goal, Sans had fallen back to his old strategy, the one that had worked for the most part on the flower, the one that his team had dispiritedly settled on in the face of total helplessness: keep waiting. Pretend you don't remember; that will make you less of a target. Just keep waiting. The anomaly will get bored eventually, right?

Frisk had, indeed, gotten bored - or maybe they had gotten frustrated. It was hard to tell, even for Sans, who had a natural gift for reading people's faces.

Whatever the reason, at the beginning of run number six hundred and three, they had snapped.

Dust had blanketed the Underground, and Sans, paralyzed with grief like he hadn't known for almost two and a half years and afraid of the armageddon that the universe was pointing inexorably towards, had settled down in the Last Corridor to wait for the reckoning.

The fight had taken the kid nine hundred and fifteen iterations. It would have taken more, but Sans had gotten exhausted and fallen asleep at the worst possible time.

When he had awoken, it was thirty-six hours earlier. The readouts from his machine indicated that against all odds, existence had un-destroyed itself.

That run - number six hundred and four - had progressed as usual, albeit more slowly. It was obvious that something had really rattled the kid, and now they were taking their time to appreciate everything all over again. Sans hadn't consciously dared to hope, but...

At the end, there had been a LOAD. This in itself was unusual. The end of a run had always previously ushered in a single RESET, or that destruction and recreation that Sans hadn't witnessed because he was dead at the time.

Frisk had chosen to stay with Toriel, the first time around; the same thing they had chosen in every other pacifist timeline. The second time around, they had mumbled guiltily that they 'had places to go'.

Whatever Frisk had hoped to accomplish there, it hadn't worked. A succession of twelve LOADs had followed, every time with Frisk looking more and more desperate, and Sans getting antsier and antsier, waiting for the inevitable.

A RESET had indeed happened. Run number six hundred and five had been rushed, rushed, rushed. Frisk had run purposefully through Snowdin, Waterfall, and the Hotlands, not stopping for the hangouts with Papyrus and Undyne, only slowing down when they reached the MTT hotel.

Sans, still recovering from the unexpected disaster that had been the restaurant 'date' (why hadn't the 'you'd be dead where you stand' line been such a problem in run 604?!), had been sitting with Alphys in her lab, watching Frisk finish talking to Burgerpants. He hadn't known why Frisk had deemed the fast-food worker such a high priority at the time.

If Sans had to guess, he'd say that they were putting off what they did next.

The kid had walked into the CORE, and followed Alphys' directions to turn right. When she had realized the change in the schematics, they hadn't listened to her directions. They hadn't corrected their path.

"Sorry," Frisk had murmured into the phone. The two monsters shared panicked glances, and Sans had typed desperately into the computer, trying to override the CORE's configuration, while Alphys had started yelling into the phone for the human to turn back.

"Please, whatever you do, _don't jump_ \- y-you don't understand, the C-CORE won't just kill you, _it'll make it so you were never alive in the first place—_ "

"Exactly," Frisk whispered, and leapt gracefully into the abyss.

Somehow, the human had found out about the plan that had accidentally gone horribly wrong - the death of W. D. Gaster.

Which was why Sans, now in his lab with part of the machine uncovered and flashing readouts on several screens, was frantically IMing the only other person who remembered.

 **skelepton:** alphys

 **skelepton:** alphys

 **skelepton:** alphys are you there? this is important

 **skelepton:** alphys i mean it we have a serious problem

 **ALPHYS:** sorry sans... i'm here now ^.^;

 **ALPHYS:** what is it? what's wrong?

 **skelepton:** short version: human kid fell down, stole the reset ability from the weed, did over six hundred runs on an average of about a day and a half each, not including loads.

 **skelepton:** then they jumped into the core. on purpose.

 **ALPHYS:** wHAtt

 **ALPHYS:** WHY WoulD THEY

 **ALPHYS:** NOT EVEN FLOWEY LIKED PAIN

 **skelepton:** and i don't know how, but they knew exactly what it did to gaster.

 **ALPHYS:** if if the human had the reset power actively in their control

 **ALPHYS:** we cant be sure the outcome was the same

 **ALPHYS:** we couldnt even be sure if they didnt have dt because they were a human and not a monster

 **ALPHYS:** w e have to check

 **skelepton:** you're right. but that's not even the worst part.

 **skelepton:** i've been taking readings with the machine in the basement, and

 **skelepton:** i think the spatiotemporal shockwaves from the explosion

 **skelepton:** there's a significant chance that they knocked the entirety of the underground into a different universe.

* * *

Without looking, Homura could tell that a suspiciously familiar weight had resettled on her forearm. She looked anyway, just to make sure that she wasn't hallucinating.

The unexpected weight did indeed belong to her shield.

 _That doesn't make sense - I lost my time magic after Madoka -_

It was at that moment that Homura remembered the function of a save point in a video game.

 _What._

* * *

／人◕ ‿‿ ◕人＼

* * *

\- A lepton is a type of fundamental particle not affected by the strong nuclear force.  
\- I'm taking some liberties with the timeline of events re: Gaster and the True Lab.  
\- This Frisk is not dokudoki's Core Frisk.


End file.
